In making vehicle bodies and in particular truck trailer bodies, the older practice of securing the roof sheets to the roof bows by means of fastening elements such as rivets has been supplanted by the use of heat curable adhesives. Various heat curable adhesives possess sufficient bonding strength as provides an adequate securing of the roof sheet to the roof bows but the technique requires the parts to be held in clamped, assembled condition while being subjected to the heat-curing cycle, typically a cycle involving approximately 20 minutes at 180.degree.F. Obviously, such a process is time consuming and requires a complex clamping arrangement and it would be advantageous to obtain a more simple and less time consuming process.
To this end, it has been proposed to utilize a hot melt adhesive to replace the heat-cured adhesive but two problems are presented by the use of hot melt adhesives. First of all, commercially available hot melt adhesives have proven to provide an unacceptably low bonding strength between the roof bows, conventionally aluminum structural members, and the aluminum roof sheets and, further, unless the roof bows are subjected to a preheating cycle to raise their temperature to 150-200.degree.F, the hot melt adhesive cools and sets too rapidly once applied to the roof bows as does not allow adequate time in which to place the roof sheet in position and press it against the roof bows to spread the adhesive. For example, with the roof bows at room temperature it has been found that after the hot melt adhesive has been applied there is not more than about 5-10 seconds available within which to bring the roof sheet into proper position and to press it against the roof bows. Moreover, as noted above, the resultant structure does not possess adequate bonding strength.